Please add the ability to filter invoices based on the Billing Type of the associated matter (e.g., Hourly, Flat Fee, Contingency, etc.). The Invoices page currently allows filtering by Invoice Type (Trust Balance, Credit Request, Invoice), but it does not provide a way to filter invoices by the billing type assigned to the matter. As a result, users who need to report on or export invoices for a specific billing type must export all invoices and manually review each one to determine whether it belongs to a Hourly or Flat Fee matter.